Process of engraving printing-surfaces



r M. BRADLEY.

Process of Engraving Printing Surfaces; v

'No. 225,457. Patentedv Mar. 16, 1880. I

UNITED STATES PATENT Orrrc.

MILTON BRADLEY, OF SPRINGFIELD, MASSACHUSETTS.

PROCESS OF ENGRAVING PRINTING-SURFACES.

SPECIFICATION forming part of Letters Patent No. 225,457, dated March16, 1880. Application filed February 2, 1878.

T0 allwhom it may concern: I

Be it known that I, MILToN'BRADLEY, of Springfield, county of Hampdenand Commonwealth of Massachusetts, have invented a new and usefulProcess for Engraving on Wood, Metal, or other Surfaces for printingtherefrom; and I do hereby declare that the following is a full, clear,and exact description of the same, reference being had to theaccompanying drawings, making a part of this specification, in which-Figure l is a front view, and Fig. 2 a side View, of the cuttingmechanism of an ordinary engravers ruling-machine as used for makingrelief-printing plates, such as engravings on wood. Fig. 3 representsthe printing-surface of a block or plate, B, engraved with the mechanismshown in Figs. 1 and 2, after having been prepared in the ordinarymanner. Fig. trepresents the printingsurface of a block or plate, B,which was prepared according to my process and afterward engraved withthe above named mechanism. Fig. 5 is an enlarged cross-section of aportion of block or plate B on line as y, showing portions of thecutting mechanism in operative positions at different portions of theartificial surface superimposed upon the face of the block or plate B bymy process. Fig. 6 is a similar cross-section after having been engravedby my process.

In all the figures the same letters of reference designate identicalparts. I

In order to more clearly describe my process, I will first brieflyexplain the ordinary method of engraving.

Original engraved plates of wood or metal for printing, known asrelief-plates,'are made by first preparing a plane surface and thenremoving such portions as are not to print-i. a, not to receiveinkleaving all the printinglines and portions at the original height ofthe surface. When prepared mechanically, as distinguished from etchedand photo-relief plates,

--the parts which are to appear white when printed on white paper arecut away with graving-tools, either in the hands of engravers or insuitable machines. I

In engravings of mechanical and architectural subjects the fiat andcylindrical surfaces are much better and more rapidly engraved has a Vor diamond point andhencethe deeper I it cuts into the material or blockB the Wider the line removed at the surface.

The depth of the cut in the block is regulated and controlled by thefoot 0, which bears on the surface of the block 13, and is adjustedvertically relatively to the cutting-tool A by the screw D passingthrough and working in the support E, to which the tool A is positivelyattached by the set-screw F,

The operation of engraving with a rulingmachine is as follows: Thedesired depth of out having been decided upon and secured by theadjustment of the foot 0 to the tool A, the foot is held firmly downonto the surface of the block to be engraved by the hand of the engraverwhile it is being moved across the block by means of some suitablemechanism, such as a rack and pinion. One line having been engraved, theblock is moved a suitable distance and another line parallel to thefirstis engraved, as before, and so on over the surface to be engraved.If a uniform tint is desired, the block must be advanced exactly thesame distance each time, and the relative adjustment of the foot 0 tothe tool A must remain constant; but if a cylindrical surface is to'berepresented the movement of the block and the adjustment of the foot tothe tool must be varied and regulated by the skill of the operator; andwhen the parts are adjusted for a given line they must remainundisturbed throughout the whole length of that line, in order toproduce a uniform thickness or width of line, for the reason that theamount of skill and labor required to adjust the tool by hand during itscutting action would be so great as to rendersuch adjustmentimpracticable and unprofitable.

In Figs. 3 and 4 the black-lines represent the raised or printingsurface of the block.

By my process the clouded appearance in I when the V-shaped toolA israised relatively to the surface of the block the white line cut away ismore shallow and narrower, and when the tool is depressed the cut isdeeper and wider, so that when the tool is raised the printed tint isdarker, and when depressed lighter. To accomplish this raising anddepressing of the tool with regularity and method, I apply to thesurface to be ruled some foreign substance, makingthe body of thesubstance, when applied, thickest where the shades are to be darkest,and leaving the block bare, or nearly bare, at those parts which are toprint the lightest tints. In Fig. 5 the black portionsH H H representsome suitable substance, as above described, which may be a gum orresin, or other substance which can be dissolved and applied with abrush, the thicker portions being produced by repeated coats. For somepurposes sheetgelatine or a like form of material may be applied to formthe necessary raised surface, and I do not limit my invention to the useof any specified material, as the .kind of substance to be applied inany particular case will, of necessity, vary with the requirements ofthe particular work in hand and the varying effects to be produced.

Two positions of the cutting-tool A and foot 0 are shown in Fig.5. Inone position, at t', the foot 0 rests on a portion of the block nearlyor quite uncovered by the gum or varnish, and consequently the tool Acuts deep into the block, while in the other position, at k, the foot ison a thick portion of the gum,

and thereby the tool is nearly or quite removed from the block.

In Fig. 6 portions H H H of the gum are shown as remaining on the block;but in practice the gum nearly all crumbles off during the process ofruling, as the lines are usually ruled much nearer together thanrepresented in the enlarged sectional views, Figs. 5 and 6.

If any of the gum remains on the block after engraving, it may beremoved by carefully scraping and rubbing either' dry or slightlymoistened.

To still further facilitate the work of the artist, the coating may beslightly colored, so that the thicker it is applied the darker it willappear, thereby enabling him to see just what effect he is producing;but this is not necessary to the perfect operation of the process.

The desired shades having been modeled on the surface of the block, asabove described, the engraving is done with the ruling-machine withoutmore necessary care than is requisite in ruling a plain tint by ordinaryprocess.

The machine may be so arranged as to rule straight lines, as shown inFig. 4, or, by a wellknown mechanism common to rulin g-machines, thelines may be somewhat waved or serpentine. My process is equallyapplicable to both styles of ruling.

It will be seen that, as the bearing portion m of the foot 0 must be ofsome appreciable size and somewhat removed from the point of the tool A,the location of the shades produced on the ruled block will be removedfrom the location of the corresponding raised portions of the model bythe distance of the portion m of the foot from the point of the tool,and also all the shaded portions will be enlarged from the correspondingraised portions of the model by the diameter of the portion m; but as inany one machine these proportions are constant the effect can be easilyforeseen and provided for by the artist. A plate, after being engravedby my process, may be more completely finished by handengraving, and insome cases must necessarily be, as is the case with any ruled work.

By a proper adaptation of the machine to the effect required and theexpenditure of a comparatively small amount of hand-labor, a very closeimitation of a hand-engraved surface can be produced by this process ata very great saving in time and by a much less skillful workman.

Now, having fully described my invention, what I desire to secure byLetters Patent is 1. The method of producing clouded or irregularengraved surfaces by an engravingmachine, consisting in the applicationto the surface to be engraved of a foreign substance varying inthickness at different points to correspond with the depth of cutrequired.

2. As an improvement in the art of engraving clouded or irregularsurfaces by machinery, the employment of an irregular or uneven surfaceof wax or like material to govern the depth of cut of the graving-tool,substantially as described and shown. I

3. A prepared block or plate to be cutin an engraving-machine, havingits face provided with a foreign substance varying in thickness atdifferent points according to the different depths of cut required.

MILTON BRADLEY.

Witnesses:

JAS. M. BRYAN, E. H. DARLING.

